Our long-range goal is to develop systematic procedures for the identification of DNA damage occurring at the level of a few parts per million. We are emphasizing the determination of the structures of compounds produced in the reaction of cross-linking agents with DNA. We will continue to focus our attention on the reactions of diepoxybutane with nucleosides and DNA. The structures of the products we have isolated will be determined using microgram quantities, if necessary. This will be done using information from ultraviolet, nuclear magnetic resonance, and mass spectra, pKa values and chemical transformation. A catalog of ultraviolet and pKa data for bases, nucleosides, and their mono- and dialkyl derivatives is being assembled. We hope to produce a set of tables, and a rulebook, which will be made generally available. It should be possible to plug in wavelength and dissociation data directly, and obtain maximal structural information by a simple procedure. In order to complete our catalog, we are attempting the synthesis of certain unknown substitution products of the base components of DNA, such as 3,7-dimethylguanine and 1,06-dimethylguanine. The structures of the reaction products of acrolein with cytosine and guanine will be determined. The reactions of acrolein with other bases and nucleosides will be investigated.